Cross-connecting cabinet



S pt 19, 1961 H. M. FlTZPATRlCK 3,001,103

CROSS-CONNECTING CABINET Filed May 13, 1959 2 Sheets-Sheet 1 P 19, 1961H. M. FlTZPATRlCK 3,001,103

CROSS-CONNECTING CABINET Filed May 13, 1959 2 Sheets-Sheet 2 UnitedStates Patent 3,001,103 CRDSQNNECTING CABINET Harold MelvilleFitzpatrick, Essendon, Victoria, Australia,

assignor to Electrical Qommunication Enterprises Pty- Limited, Essendon,Victoria, Australia Filed May 13, 1959, Ser. No. 812,966 Claimspriority, application Australia May 14, 1958 21 filaims. (Cl. 317%99)This invention relates to enclosures or cabinets for multi-wireelectrical cable terminals and refers especially to such enclosures andcabinets which are designed to house and protect from accidental damageand atmospheric conditions the cross-connections between terminals ofseveral multi-wire cables. Such enclosures or cabinets are herinafterreferred to as cross-connecting cabinets. The invention also includes animproved terminal unit for use in a cross-connecting cabinet and animproved arrangement for elfecting the cross-connections.

Cross-connecting cabinets are commonly used in wire communicationnetworks to provide easily accessible terminations for individualconductors of one or a number of cables at a common point.Cross-connections between the various condutcors may be made and alteredat this point, thus rendering the cable network adaptable for changingrequirementsof use, reducing the lengths of cable needed andfacilitating maintenance and fault-tracing in the network.Cross-connecting cabinets normally enclose many pairs of individualcommunication circuit terminals, which are located in close proximity toeach other. Accordingly the insulation resistance between the terminalsof different circuits should be maintained at a high value in order toprevent cross-talk and shortcircuits, caused by leakage between thevarious terminals, with the consequent degrading of the electricalcharacteristics of the whole network.

Presently used cross-connecting cabinets are generally either ventilatedor hermetically sealed. Cabinets of the former type suffer from thedisadvantages that the humidity of air inside thecabinet is the same asthe humidity of' the air outside the cabinet and that dust and other 7foreign matter may enter into the cabinet. If such vent-ilated cabinetsare located out of doors, changing atmospheric conditions may causeconsiderable condensation of moisture inside the cabinet. Accumulationof moisture between the terminals of different circuits assists theformation of leakage paths therebetween and accordingly a reduced andoften varying insulation resistance between the varying circuitsresults. Under extreme atmospheric conditions, and during floods, theelectrical leakagemay become so marked that the whole network becomesinoperable.

Presently used hermetically sealed cross connecting cabinets usuallyemploy an elastic compression seal lo- .cated around a door or otheropening through which access to the cabinet may be gained. These sealsare rarely effective in use since the cabinets are generally of a lightconstruction and thus the wall of the cabinet, or the door itself oftentends to warp or buckle under the compressive force exerted by the seal.The seals may also fail to adhereto the cabinet after being in use forsome time and tend to develop a permanent set thereby becomingineffective. if the door or opening is located in a-horizontal plan,then dirt, dust and other foreign matter may enter the cabinet and lodgebetween the sealing surfaces, there by impairing the quality of theseal. Cross-connecting cabinets with leaking seals sufier from the sameprincipal disadvantage of condensation as described above with referenceto ventilatedcabinets.

It is the principal object of the present invention to provide animproved cross-connecting cabinet of'the hermetically sealed type inwhich the abovementioned disadvantages are overcome.

Another object of the invention is to provide a hermetically sealedcross-connecting cabinet in which the terminal units can be arrangedcompactly so as to reduce as far as possible the amount of enclosed airthereby minimizing the condensation of moisture within the cabinet.

A further object of the invention is to provide a hermetically sealedcross-connecting cabinet in which the seals are adapted to withstandvibrations and minor shocks, without impairing their efficiency.

Yet another object of the present invention is .to provide ahermetically sealed cross-connecting cabinet which is adapted toaccommodate a varying number of cables and in which thecross-connections between the terminals of the cables are effected in asystematic and easily traceable manner.

Further objects and aims of become apparent from the ensuing ticularembodiment thereof.

According to the invention, a cross-connecting cabinet of thehermetically sealed type comprises a base portion having a cylindricalsurface adapted to receive a rolling ring seal, a face containingcircular apertures adapted to receive rolling ring seals whereby eitherterminal units and/ or sea-ling plugs may be retained and hermeticallysealed therein, a cover adapted to fit over the base portion, a rollingring seal on the said cylindrical surface adapted to be rolled into asealing position between .the said surface and the cover by movement ofthe cover over the base portion in the axial direction of the saidsurface, means to locate, guide and move the cover over the baseportion, and means to secure the cover in position on the base portion.

I Accordingto one aspect of the invention the said means comprise aflexibly supported hollow column on the cover and a spindle .on the baseportion adapted to fit within said hollow column. A further hollow outercolumnmay be provided on the base portion to fit over the said hollowcolumn.

According to a furtheraspect of the invention a terminal unit for use inthe cabinet may comprise an elongated prismatic body member ofdielectric material having a central longitudinal recess and one or morelongitudinally disposed shoulders on each side of the groove, terminaltags located on these shoulders and a further series of tags which arestaggered in relation to the terminal tags and are mounted adjacent thesaid central recess. The terminal unitsare arranged to extend indirections parallel to the longitudinal dimension of the cabinet and aresupported by a series of guard members hereinafter called jumper guardswhich are attached to the base portion and the hollow out-er column. Theconnection between the jumper guards and the terminal units are madethrough rings on the jumper guards, hereinafter called jumper rings,which are designed to fit within, and be secured to, the base or innersurface of the recess in the terminal unit. These jumper rings alsoserve to locate the crossconnecting or jumpering wires within the recessof each terminal unit.

To facilitate the cross-connecting of corresponding terminals ofadjacent terminal units, the terminals on each terminal unit arepreferably arranged so as to provide an inner and an outer terminal.Corresponding inner terminals of adjacent terminal units may be directlyconnectedby a removable conducting link, and similar connections may bemade between corresponding outer terminals of adjacent terminal units.The arrangement .of the terminals to provide an inner and an outerterminal is conveniently achieved by bringing out each pair .ofconductors to a pair of terminal tags and mounting the the presentinvention will description of a parengaged-with the cabinet,

wires hereinafter jumper guards 16 are removably attached to the baseporand about avertical axis.

7 of these jumper tags on a stepped base, or alternatively by making theinner tags longer than the outer tags. For ease of manufacture, handlingand sealing the body of the cabinet is preferably-circular in horizontalcross-section.

Various other features and advantages of the invention will now'bedescribed with reference to the, presently preferred embodiment of theinvention which is illustrated'in the accompanying drawings, in'whichzFIGURE 1 is a side elevation ofa cross-connecting cabinet in the closedposition, the broken lines indicating the extent to which the cover maybe raised while still .;FIGURE 2 is an enlarged crossse ctional view-ofthe .cabinetshown in FIGURE 1, showing also the crosssection of aterminal unit and a sealing plug,

..FIGURE 3 is a-sectionalview along the line 33 in FIGURE 2, and VFIGURE 4 is a sectional perspective view of two adjacent terminal unitsshowing the method of direct crossconnection between corresponding tagsthereon.

In this arrangement, the body of the cabinet isgenerally cylindrical inform and comprises three main partsbase '5, cover 6 and cap 7which arecast from aluminum alloy, or' other suitable material, and sand blastedon theirexternal surfaces to give a uniform mat finish. The base portionof the cabinet is in the form of a hollow cylinder having its upper endclosed and its lower end provided with flanges 8, whereby the base canbe secured to a foundation. The upper face of the base 5 is providedadjacent its periphery with several upwardly directed equally spacedcircular apertures 9 which are adapted to receive and retain in positioncable ter-" The cover 6 is adapted to fit over the terminal units 10 andengage with the base portion 5 of the cabinet, thus completely enclosingthe terminal units 10. The upper end ofthe cover 6 is providedexternally with a captive nut 21, which is provided with a flange 22,which underlies an annularshoulder 23 on a member 24, which is rigidlymounted on the upper end of the cover 6.' The captive nut 21' isarranged to threadably engage the shank portion 14 of the spindle 13,and is provided with a compressible ring seal 25 of resilient 'material,or alternatively, a rolling elastomeric ring may be used to elfect thesealing between the spindle 13 and the cover 6. The compressible ringseal 25 is designed to minimise relative motion between it and the metalsurfaces confining it, when the ring seal 25 is compressed, as thiscould damage it especially after repeated closing and opening of thecover 6. This seal'25 is adapted, on tightening of the nut 21, tocompletely seal the portion of the cover 6 through which the spindle 13projects. The internal diameter of the ring seal 25 is greater (when theseal-is not under compression) than the external diameter of the shankportion 14 of the spindle to enabl the latter to move freely through thering seal when the cover is being raised and lowered. 133; such ascrewing action the cover 6 is forced downwardly over the outer surfaces26of the base. portion 5, Where it is "arranged to engage with a rollingneoprene ring seal 20, which provides an airtight joint between thecover 6 and the base portion 5 of the cabinet.

The cover is provided witha cap 7 which is adapted to threadably engagethe externally projecting shank portion 14' of the spindle 13- The cap 7is fitted with a minal units 10, or specially provided sealing plugs 11,

,which are used to close the apertures when there are fewer terminalunits used than there are apertures. A

' hollow,.vertically disposed column 12 is rigidly fixed t0 the centreof the base portion 5, and is provided internally with a co axialspindle 13, which extends to at least the height of the hollow outercolumn 12, and has an externally screw-threaded shank portion 14 at itsupper end. The spindle 13 is of such dimensions as to enable it topenetrate inside another hollow column, hereafter'called the innercolumn 15, which is attached to the cover 6 of the cabinet and fitsloosely over the said spindle 13. The loose sliding engagement betweenthe inner column 15 and the spindle 13 helps to guide the cover 6 on tothe base5. Attached to the hollow outer column 12 and the-baseportion'Sthere is a system of spaced vertical referred to as jumperguards 16. These tion 5 of the cabinet and are adapted to supportterminal units 10in position by orientating them in a vertical plane Thejumper guards 16 also serve as a convenient place to which cable sheathsor screens can be connected for earthing purposes. Each guards 16 hasseveral horizontally disposed rings, hereinafter referred to as jumperrings 17, attached to it, which act as guides for cross-connectingjumpering wires as described hereinafter. The terminal units 10, and anysealing plugs 11 used when there are insufiicient terminal units to fillall the apertures 9 in the base portion 5, are provided with rollingelastomen'c ring seals 18, which provide an airtight joint between thebase portion 5 of the cabinet and the terminal units 10 or sealing plugs11. g

:The cover 6 of the cabinet is, bell-shaped and provided internally witha hollow axial inner column 15, as referred to above, which is adaptedto fit inside the hollow column provided on the base portion 12, andslide tumbler lock 27, enabling the cabinet to be made secure after thecap 7 has been screwed down. Removal of they cap gives access to thecaptive nut 21 'on, the top of the cover. By unscrewing the nut theflange 22 on the same raises the cover off the base, after relaxing thering sealing member 25 surrounding the shankrportion 14 of the spindle.When the cover is raised in this way, the rolling ring seal 20betweenthe cover and the base is rolled to a loose or non-activeposition in the groove 28 and the nut 21 is then further unscrewed'untilit disengages from the shank 14 of the spindle, whereupon the cover canbe raised to a position where the enclosed ter minal'units 10 are fullyaccessible. The cover is held in this'raised position by aspring-controlled latch 29, which:

section, generally in the form of a truncated sector of a circle. Theouter surface of each unit is formed in a stepped configuration and thecentral portion of the said surface is recessed to provide accommodationfor jumpering wires as referred to hereinafter. on each side of, and thesaid recess 32 in, the unit are so disposed as to provide a radiallysymmetrical horizontal section. The terminal unit, when placed inposition vertically in an aperture in the base portion of the cabinet,is secured in its vertical position by rings 17 which are themselvesattached to a jumper guard 16. The terminal tags 33 of the terminal unitare-disposed in straight lines, one line on each step of the terminalunit. side of the recess 32, separate lines of inner and outer tags,.theinner tags 34 being disposed adjacent the recess and projecting radiallyoutwards beyond the outer tags 35 which are located on the steps remotefrom the recess. A multi-wire cable 36 enters a terminal unit through acylindrical base portion 37 from below, and the individual conductors,which may be. either dry paper or plastic insulated, are then connectedto the corresponding terminal tags on the terminal unit,

The steps 30, 31'

means of jumper Thus, on each terminal there are, on each theseconnections being embedded withinthe epoxy resin which ,forms the bodyof the terminal unit. The moulded body of the terminal unit alsoprovides an airtight seal for the cable, which is essential if the cableis gas-filled. The epoxy resin used has a high order of volume andsurface resistivity, and thus provides for good insulation between thetags.

Where the cable is provided with a @metal sheath or screen, provision ismade to earth this sheath or screen by attaching it to metal inserts inthe terminal units, which inserts are connected through the jumperguards 16 to themetal body of the cabinet.

The stepped form of the terminal unit permits the use of directconnections between corresponding tags on adjacent terminal units bymeans of solid connecting links 38, thus greatly simplifying thecross-connecting circuitry. Each terminal "unit is further provided withtwo vertical rows of tags of insulating material, referred to as fanningstrips 39. These rows or fanning strips are disposed-on either side ofthe central recess in the terminal unit, and the tanning tags arestaggered, in a vertical direction, in relation to the terminal tags, sothat the cross-connecting orjumpering wires can be supported by thesefanning tags without coming into contact with nearby terminal tags. Thecentral recess in each terminal unit is adapted to receive thesejumpering wires and lead them either upwardly or downwardly, either toother terminal tags on the same terminal unit, orto terminal tags onanother terminal unit within the cabinet. This recess .32 in eachterminal unit, is alsoslotted horizontally to receive the jumper rings17 attached to the jumper guard 16, which rings further serve to confinethe jumpering wires within the central recess 32. The stepped formationof the portion of the terminal unit body on which the adjacent rows ofterminal tags are mounted also has the beneficial effect of greatlyincreasing the surface leakage path between these rows of tags.

According to an alternative embodiment of the invention the base portionmay be formed as a conduit enclosing the lead-in cables and embeddeddirectly in concrete or any other suitable foundation.

In a modified form of the invention, the fanning tags, jumper rings andjumper guard may be made integrally as one unit. This integral unitcomprises a channelshaped metal member, extending the length of theterminal unit and adapted to be inserted in, and attached to the bottomof, the central recess of said terminal unit, and a jumper guard whichis integrally attached to the said channel member by severalsemi-circular brackets. The walls of the channel section extend outwardsbeyond the body of the terminal unit fora distance approximately equaltothe depth of the central recess in the body of the terminal unit. Theportions of the walls of the channel member extending outwards beyondthe body of the terminal unit are symmetrically slotted along theirwhole length to provide a series of spaced outwardly directed fingers,which are used to fan out the jumpering Wires of the terminal unit. Thejumper guard is preferably attached to the channel member throughseveral semicircular brackets which are welded to corresponding fingers,referred to above. A fanning tag and jumper guard assembly of the typedescribed above stifiens considerably the terminal unit and simplifiesthe manufacture thereof, and this is especially advantageous as theepoxy casting resin used takes about three days to harden completelyafter moulding, and in that time could easily bend, twist or warp if notstifiened. Further, the metal fanning tag and jumper guard assemblyprovides a convenient earthing point for the sheath of the cable, andalso serves to protect the terminal unit during handling and transportprior to insertion in a cross-connecting cabinet.

Miniaturised square section tinned steel terminal tags have beenadoptedto enable a tool, which requires: a tag of this form, to be used forconnecting the jumpering wires to the tags by a solderless wrappingtechnique. lCon-ventional'soldering methods can also be used on thesetags.

The cross-connection between corresponding tags on adjacentterminalunits canbeeftected by means of charlnel-shaped jumper links, which .areplaced in position over the corresponding terminal tags and soldered-tothem Tags which bear important circuits, such as burglar or fire alarms,are normally covered by a piece of insulating tubing in order to preventthese circuits from being accidentally short-cireuited or earthed duringmaintenance operations on the cabinet.

"Ihe cross-connecting cabinet as described above is eminently suitable'for the housing of cross-connections of communication cables. It iseasily accessible, sufliciently strong to resist accidental damage fromvibrations and shock, and withstand submerging in water, i.e. it isflood: proof. The sealing arrangements ensure that changing atmosphericconditions do not affect the terminal connections in any Way. The sealsare easily accessible and easy to maintain in a good condition. It isimportant to achieve complete hermetic sealing of the terminal units,because the condensation of moisture from theair on to the surfaces ofthe units could provide a short-circuit path between the tags. Thestepped terminal unit construction and the use of epoxy casting resingreatly improves the insulation resistance between adjacent rows oftags, as well as rendering possible the simple direct connection betweencorresponding tags in adjacent units described herein. The jumperingwires are disposed in the unit recesses, and this renders subsequentmaintenance and inspection work much easier than in'presently usedcross-connection systems, as well as protecting the jumpering wires fromaccidental damage during such work. The cross-connecting cabinet asdescribed herein has also a great degree of flexibility, as the numberof circuit terminals to be enclosed can be varied widely by using therequired number of terminal units only, and inserting sealing plugs inthe unoccupied apertures .in the base. portion of the cabinet.

What I claim is:

l. A cross-connecting cabinet of the hermetically sealed type comprisinga base portion having a cylindrical surface adapted to receive a rollingring seal, a face containing circular apertures adapted to receiverolling ring seals whereby terminal units and sealing plugs may beselectively retained and hermetically sealed therein, a cover adapted tofit over the base portion, a rolling ring seal on the said cylindricalsurface adapted to be rolled into a sealing position between the saidsurface and the cover by movement of the cover over the base portion inthe axial direction of the said surface, means to locate, guide and movethe cover over the base portion, and means to secure the cover inposition on the base portion.

2. A cross-connecting cabinet as claimed in claim 1,

in which the first said means comprise a longitudinally extending hollowcolumn attached centrally to the inside of the cover and a centrallylocated upwardly directed spindle adapted to fit within said hollowcolumn with slight clearance.

3. A cross-connecting cabinet as claimed in claim 2, in which the hollowcolumn is attached to the cover in a partspherical ball seating, whichallows the hollow column to pivot at its point of attachment to thecover.

4. A cross-connecting cabinet as claimed in claim 2, in which thespindle extends through the cover when the cover is in the closedposition and forms an externally screw-threaded shank portion.

5. A cross-connecting cabinet as claimed in claim 4, in which the coverincludes an internally screw-threaded portion, which is adapted toengage the shank portion of the spindle.

6. A cross-connecting cabinet as claimed in claim 5, in which the saidinternally screw-threaded portion com.- prises a nut which is free torotate about a fixed axis but is held translationally captive relativeto the cover.

7. A cross-connecting cabinet as claimed in claim 2, in which the coverincludes a protected compression seal, adapted to seal the cover againstthe spindle when the cover is in the closed position.

7 comprising horizontally which the rolling ring seal is displaced whenthe cover is lowered.

9. A cross-connecting cabinet as claimed in claim 2, in whichthe firstsaid means also includes a hollow outer column, which is concentric withthe spindle and is adapted to receive the said hollow column on thecover with a slight clearance. I

10. A cross-connecting cabinet as claimed in claim 9, comprising aspring-controlled latch which is adapted to support the cover in theraised positionand which is attached to the hollow outer column.

11. Across-connecting cabinet as claimed in claim 9 comprising asystemof longitudinally extending jumper guards attached to the hollow outercolumn and the base portion of the cabinet. a 7

12; Across-connecting cabinet as claimed in claim 11,

disposed jumper rings and terminal units connected to the jumper guardsby means of said horizontally disposed jumper rings.

13. A cross-connecting cabinet as claimed in claim 12, in which theterminal units each comprise a longitudinal prismatic body portion ofdielectric material, having two or more longitudinally extending rows ofterminal tags.

14. A cross-connecting cabinet as claimed in claim 13,

in which the dielectric body portionof a terminal unit is provided witha central, longitudinal recess, to a surface to which said jumper ringsare connected.

15. A cross-connecting cabinet as claimed in claim 14, comprising atleast one row of terminal tags arranged on each side of the centralrecess.

tudinal direction of 16. A cross-connecting cabinet as' cla'imed inclaim 15, comprising a plurality. of rows and longitudinally extendingsteps formed in the dielectric body portion.

17. A cross-connecting cabinet as claimed in claim 16,

in which the arrangement of terminaltags on a terminal unit, and thearrangement of terminal units in the base portion of the cabinet, aresuch that corresponding tags of adjacent terminal units may be connectedby direct rigid, conducting links. r r V 18. A cross-connecting cabinetas claimed in claim 17, in which the terminal units include, on; eachside of the central recess, a row of fanning tags. 19. Across-connecting cabinet'as claimed in claim 18, in which the fanningtags are staggered, in the longithe terminal unit, in relation to .theterminal tags.

20. A cross-connecting cabinet as claimed in claim 19, in which thefanning tags, jumper rings and jumper guard are formed integrally as oneunit, which is attached to a surface of the central recess in a terminalunit.

. 21. A cross-connecting cabinet as claimed in claim 6, comprising alock and in which the means to secure the cover in position on the baseportion comprisesa cap which is adapted to be screwed on to the shankportion of the spindle and retained in a tightened position thereon bymeans of said lock. 7

References Cited in the file of this patent

